feat(wallets): add channel option for phone signer OTP delivery

[maxsch-xmint]

Description

Adds an optional channel option to the phone signer configuration so that OTPs can be delivered via WhatsApp as well as SMS.

• PhoneSignerConfig now accepts channel?: "sms" | "whatsapp".
• The phone signer descriptor includes channel in the internal signer config.
• NcsSigner.sendMessageWithOtp forwards channel in the request:start-onboarding payload.
• @crossmint/client-signers StartOnboardingPayloadSchema.request.data allows an optional channel field.
• WalletFactory merges the client-supplied channel back into API-returned phone signer configs, since channel is a client-only field that does not round-trip through the wallet-creation API.
• Added changeset for @crossmint/client-signers and @crossmint/wallets-sdk.

Test plan

• pnpm lint passes.
• pnpm --filter @crossmint/wallets-sdk... build succeeds.
• pnpm --filter @crossmint/wallets-sdk test:vitest passes, including the new phone signer channel test.

Package updates

• Changeset added: .changeset/whatsapp-channel.md bumps @crossmint/client-signers and @crossmint/wallets-sdk as minor.

Cross-repo dependencies

• This PR pairs with Crossmint/open-signer#211 (TEE channel support) and Crossmint/open-signer#212 (frame forwarding of channel), and Paella-Labs/crossbit-main (relay validation/forwarding of channel).

Link to Devin session: https://crossmint.devinenterprise.com/sessions/616ce59b2b1146ab96dd633e551f838e
Requested by: @maxsch-xmint

[devin-ai-integration]

Original prompt from Max

We are expanding the ncs otp delivery channel in case of phone signers. We will allow the channel to be whatsapp.
in the @Crossmint/open-signer repo open a new branch. we need on the start-onboarding to allow a new channel parameter that defaults to "sms" to be forwarded all down to the sms service in the tee, and when calling the twilio sdk we send this param in the channel field.
For @Crossmint/crossmint-sdk, when you call useSigner with a phone signer, you specify whether to use phone or WhatsApp.
Make the necessary changes in @Paella-Labs/crossbit-main as well.

[devin-ai-integration]

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[changeset-bot]

🦋 Changeset detected

Latest commit: d36cf5d

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 10 packages

Name	Type
@crossmint/client-signers	Minor
@crossmint/wallets-sdk	Minor
@crossmint/client-sdk-react-base	Patch
@crossmint/client-sdk-react-native-ui	Patch
@crossmint/client-sdk-react-ui	Patch
@crossmint/wallets-quickstart-devkit	Patch
@crossmint/wallets-playground-react	Patch
@crossmint/wallets-playground-expo	Patch
@crossmint/auth-ssr-nextjs-demo	Patch
@crossmint/client-sdk-nextjs-starter	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[greptile-apps]

Prompt To Fix All With AI

### Issue 1
apps/wallets/quickstart-devkit/app/providers.tsx:302
The raw query-param string is spread into the SDK config without checking it's one of the accepted `"sms" | "whatsapp"` values. `createOnLogin` is typed as `any`, so TypeScript won't catch this, and an invalid value (e.g. `?channel=telegram`) will sail past the client and be rejected by the TEE's Zod schema with a cryptic validation error instead of an early, human-readable one.

```suggestion
    const rawPhoneChannel = searchParams.get("channel");
    const phoneChannel =
        rawPhoneChannel === "sms" || rawPhoneChannel === "whatsapp" ? rawPhoneChannel : undefined;
```

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "undo" | Re-trigger Greptile}